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. 2020 May 1;138(5):553-559.
doi: 10.1001/jamaophthalmol.2020.0673.

Association of Long-Duration Spaceflight With Anterior and Posterior Ocular Structure Changes in Astronauts and Their Recovery

Brandon R Macias  1 , Nimesh B Patel  2 , C Robert Gibson  3 , Brian C Samuels  4 , Steven S Laurie  1 , Christian Otto  5 , Connor R Ferguson  6 , Stuart M C Lee  1 , Robert Ploutz-Snyder  7 , Larry A Kramer  8 , Thomas H Mader  9 , Tyson Brunstetter  10 , Michael B Stenger  11
Affiliations

Association of Long-Duration Spaceflight With Anterior and Posterior Ocular Structure Changes in Astronauts and Their Recovery

Brandon R Macias et al. JAMA Ophthalmol. .

Abstract

Importance: During long-duration spaceflights, nearly all astronauts exhibit some change in ocular structure within the spectrum of spaceflight-associated neuro-ocular syndrome.

Objective: To quantitatively determine in a prospective study whether changes in ocular structures hypothesized to be associated with the development of spaceflight-associated neuro-ocular syndrome occur during 6-month missions on board the International Space Station (ISS).

Design, setting, and participants: The Ocular Health ISS Study of astronauts is a longitudinal prospective cohort study that uses objective quantitative imaging modalities. The present cohort study investigated the ocular structure of 11 astronauts before, during, and after a 6-month mission on board the ISS.

Main outcomes and measures: Changes in ocular structure (peripapillary edema, axial length, anterior chamber depth, and refraction) hypothesized to be associated with the development of spaceflight-associated neuro-ocular syndrome during 6-month missions on board the ISS were assessed. Statistical analyses were conducted from August 2018 to January 2019.

Results: Before launch, the 11 astronauts were a mean (SD) age of 45 (5) years, a mean (SD) height of 1.76 (0.05) m, and a mean (SD) weight of 75.3 (7.1) kg. Six astronauts did not have prior spaceflight experience, 3 had completed short-duration missions on board the Space Shuttle, and 2 had previous long-duration spaceflight missions on board the ISS. Their mean (SD) duration on board the ISS in the present study was 170 (19) days. Optic nerve head rim tissue and peripapillary choroidal thickness increased from preflight values during early spaceflight, with maximal change typically near the end of the mission (mean change in optic nerve head rim tissue thickness on flight day 150: 35.7 μm; 95% CI, 28.5-42.9 μm; P < .001; mean choroidal thickness change on flight day 150: 43 μm; 95% CI, 35-46 μm; P < .001). The mean postflight axial length of the eye decreased by 0.08 mm (95% CI, 0.10-0.07 mm; P < .001) compared with preflight measures, and this change persisted through the last examination (1 year after spaceflight: 0.05 mm; 95% CI, 0.07-0.03 mm; P < .001).

Conclusions and relevance: This study found that spaceflight-associated peripapillary optic disc edema and choroid thickening were observed bilaterally and occurred in both sexes. In addition, this study documented substantial peripapillary choroid thickening during spaceflight, which has never been reported in a prospective study cohort population and which may be a contributing factor in spaceflight-associated neuro-ocular syndrome. Data collection on spaceflight missions longer than 6 months will help determine whether the duration of the mission is associated with exacerbating these observed changes in ocular structure or visual function.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr. Macias reported receiving grants from the National Space and Biomedical Research Institute during the conduct of the study and outside the submitted work. Dr Patel reported receiving grants from Wyle Laboratories during the conduct of the study. Dr. Samuels reported receiving personal fees from KBR and from Wyle Laboratories during the study period. Dr. Kramer reported receiving funding from the National Aeronautics and Space Administration (NASA) through KBR to support work on this study and also outside the submitted work. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Optic Nerve Head Minimum Rim Width and Total Retinal Thickness Quantification
Analyzed regions of interest are depicted as indicated by the colored annuli. BMO represents Bruch membrane opening.
Figure 2.
Figure 2.. Change in Minimum Rim Width (MRW) and Total Retinal Thickness (TRT)
The change in MRW (A) and global TRT (B) compared with before spaceflight (preflight) for both eyes of each participant (circles). The open circles represent data collected before spaceflight; gray symbols, data collected during spaceflight; beige symbols, data collected after spaceflight; and orange circles, 2 astronauts who had inflight optic disc edema findings. Bars indicate 95% CIs. aP < .01. bP < .001. cNot significantly different compared with before spaceflight.
Figure 3.
Figure 3.. Change in Choroid Thickness
Change in global choroid thickness compared with before spaceflight (preflight) for both eyes of each participant (circles). The open circles represent data collected before spaceflight; gray symbols, data collected during spaceflight; and beige symbols, data collected after spaceflight. Bars indicate 95% CIs. aP < .001. bP < .01. cNot significantly different compared with before spaceflight.
Figure 4.
Figure 4.. Change in Axial Length and Anterior Chamber Depth (ACD) Compared With Before Spaceflight
Change from before spaceflight was measured in both eyes of each participant (circles) using optical biometry. Bars indicate 95% CIs. All P < .001 compared with preflight.
Figure 5.
Figure 5.. Change in Cycloplegic Refraction (Spherical Equivalent)
Change after returning to Earth compared with before spaceflight for both eyes of each participant (circles). Bars represent 95% CIs. aP < .05. bP < .01. cNot significantly different.
See this image and copyright information in PMC

References

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